Although bungee jumping has been proved to be responsible for a wide range of medical problems (see previous article) it should not be assumed that use (or misuse) of bungee cords cannot ever have positive medical outcomes. A case is presented in the Journal of Cataract & Refractive Surgery which describes a patient who had his spectacles shattered by the catapulting metal end of a bungee cord – resulting in corneal lacerations from the broken glass. However, after recovery from the injury, there was a surprising outcome – the corneal laceration had produced a Radial-Keratotomy–like effect, resulting in much improved visual acuity in the damaged eye.
“The corneal lacerations appeared to induce a relaxing effect on the central cornea, thereby flattening it and improving the myopia; more severe outcomes such as globe perforation and infection were fortunately avoided. Our case not only describes one of the ocular injures related to a bungee cord, but also illustrates a surprising and un-recognized sequela of corneal trauma – myopic correction.”
Co-authors Patricia Yang and David Hu shared the Ig Nobel Prize for biology, in the year 2015, as did their urination co-authors Jonathan Pham and Jerome Choo. In the new, defecation study, Yang and Hu are joined in co-authorship by Morgan LaMarca, Candice Kaminski, and Daniel I Chu.
Here’s detail from the new study:
The above three-part illustration shows:
(A) The relationship between body mass M and the mass flow rates of food intake and excreted feces. Symbols represent experimental measurements, and dashed lines represent best fits to the data. (B) Schematic of the flow rate of energy in mammals. (C) Pie chart of the distribution of energy intake.
The authors introduce the underlying mathematics of their work with another simple illustration. They explain:
We present a mathematical model for defecation. Our system consists of a pipe whose length consists of the rectum and the colon, illustrated [here]. We model cylindrical feces of diameter D and total length L, consisting of several pieces joined like sausages. The walls of the cylinder are coated with a mucus layer of thickness h, which is considerably less than D. We parameterize the motion of feces and mucus using cylindrical coordinates… in which z represents the horizontal direction along the cylinder and r the radial direction from the center of the feces to the walls.
The paper reduces the entire flow of its argument into this dense nugget:
Animals discharge feces within a range of sizes and shapes. Such variation has long been used to track animals as well as to diagnose illnesses in both humans and animals. However, the physics by which feces are discharged remain poorly understood. In this combined experimental and theoretical study, we investigate the defecation of mammals from cats to elephants using the dimensions of large intestines and feces, videography at Zoo Atlanta, cone-on-plate rheological measurements of feces and mucus, and a mathematical model of defecation. The diameter of feces is comparable to that of the rectum, but the length is double that of the rectum, indicating that not only the rectum but also the colon is a storage facility for feces. Despite the length of rectum ranging from 4 to 40 cm, mammals from cats to elephants defecate within a nearly constant duration of 12 ± 7 seconds.
The Ig Nobel Prize citation for the earlier, urination study, explains that that earlier study tested “the biological principle that nearly all mammals empty their bladders in about 21 seconds (plus or minus 13 seconds).” The results of the new study, combined with the results of the new study, provide an enriched understanding of how mammalian output functions relate to time.
UPDATE: New Scientist magazine made a short video (and did a writeup) about this, complete with background excretion music:
— NOTTINGHAM TRENT UNIVERSITY, England
— IMPERIAL COLLEGE LONDON, England
— EPFL, Lausanne, Switzerland
— UNIVERSITY OF OSLO, Norway
— STOCKHOLM UNIVERSITY, Stockholm, Sweden
— KAROLINSKA INSTITUTE, Stockholm, Sweden
— FRI TANKE FÖRLAG, Stockholm, Sweden
— ORF (television debate), Vienna, Austria
— UNIVERSITY OF GRAZ, Austria
— UNIVERSITY OF CATANIA, Italy
— NATUURHISTORISCH MUSEUM ROTTERDAM, The Netherlands
— EDINBURGH, Scotland
The shows featured MARC ABRAHAMS (founder of the Ig Nobel Prize ceremony) and different combinations of these Ig Nobel Prize winners:
MINNA LYONS (psychopaths and night owls)
KADER ALLOUNI (using speed bumps to diagnose appendicitis)
ELIZABETH OBERZAUCHER (mathematical analysis of the man who fathered 888 children)
RAGHAVENDRA RAU (some business leaders acquire a taste for disasters that do not affect them personally)
THOMAS THWAITES (living as a goat)
LUDWIG HUBER (absence of contagious yawning in tortoises)
ALESSANDRO PLUCHINO, ANDREA RAPISARDA, CESARE GAROFALO (organizations would become more efficient if they promoted people at random)
HYNEK BURDA (defecating dogs align their body axis with Earth’s north-south geomagnetic field lines)
KEES MOELIKER (homosexual necrophilia in the mallard duck)
PIERS BARNES (how many group photos are needed to ensure at least one in which nobody blinks)
FREDRIK SJÖBERG (three-volume autobiographical work about the pleasures of collecting flies that are dead, and flies that are not yet dead)
LAURENT BÈGUE (people who think they are drunk also think they are attractive)
Of all the possible pitfalls* which can affect bungee jumpers, a compromised immune system might not be the first to spring to mind. But spring it did to the minds of David J van Westerloo, Goda Choi, Ester C Löwenberg, Jasper Truijen, Alex F de Vos, Erik Endert, Joost C M Meijers, Lu Zhou, Manuel PFL Pereira, Karla CS Queiroz, Sander H Diks, Marcel Levi, Maikel P Peppelenbosch, and Tom van der Poll, who have collectively examined, by experiment, the effects that a jump might have.
20 volunteers (naive to bungee jumping) were exposed to a bungee jump from an altitude of 60m, at the foundation teaching hospital Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.
“The study site was located at the hospital grounds, where a crane was placed. Bungee jumps took place from an altitude of 60 m, under supervision and guidance from an experienced commercial bungee jump crew. On the morning of the study day, an intravenous access catheter was placed in the cubital vein.“
Half had been previously treated with a three day course of propranolol (a beta blocker) and the control group were not. Subsequent blood analyses showed that :
“Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.”
Note that the volunteers actually did the jumps, but many showed obvious signs of stress before jumping. Therefore further studies might be needed to determine whether the immune system effects were caused by mental strain or by the physical stresses of the jump (or both).